JP2007507698A - Test system for evaluating coatings against biofouling and fluid shear forces - Google Patents

Abstract

An improved test system for evaluating coatings against biofouling and fluid shear forces.
Described herein is a test system for evaluating coatings against biofouling and fluid shear forces in natural seawater. The system comprises: a support structure that holds a plurality of test panels; (a) two or more coaxial circles about an axis and (b) a plane substantially perpendicular to the axis. A first row of spaced apart test panels disposed on the support structure, the test panels having the same or different coatings on one side, and the first row of test panels on the support structure Comprises a drive device arranged to be rotatable about said axis.
[Selection] Figure 1

Description

  The present invention relates to a test system for evaluating coatings against biofouling and fluid shear forces that can be used in natural waters such as sea water. The invention is based on the need to develop an improved rapid test system that can optimize test equipment and experimental procedures, especially for marine coatings, and that can best simulate the corrosion process in marine coatings as the ship navigates. is doing.

  The marine paint industry is experiencing dramatic changes in redefining the core technologies traditionally used in the coatings market. From the 1970s to the end of the 20th century, tributyltin (TBT) and self-polishing coatings dominated the industry, an efficient, inexpensive and high-performance marine protective coating system to prevent underwater surface contamination on ships Appeared on the market. However, the establishment of a TBT ban at that time by the International Maritime Organization (IMO) developed a new resin technology and coating formulation to achieve the same goal by combining copper oxide and a high-performance biodestructive agent. By 1 January 2003, the IMO has confirmed the TBT ban on all ships in 2008 following the TBT ban that achieved the end of production of TBT-based paints. The paint industry has come to recognize that the use of toxic compounds, i.e. indiscriminate release pollution to the marine environment due to leaching from marine paints, is a relic of the past. Other substances, such as copper oxide, may be considered harmful to marine ecosystems, although they are much less toxic than TBT.

  Marine paint manufacturers have developed new coating systems, ie, reduced copper content, preferably metal-free systems, as well as a variety of paint colors (copper oxide binders) in line with performance targets required by the marine industry. The development of unique traditional colors other than red) is being urged. Technological innovation within the industry has spurred competition for the development of excellent marine paints. This trend is evident from the numerous patents granted for new paint systems in the past few years. However, progress in the development of commercial products is hampered by the extremely long period of sea exposure panel testing required to demonstrate the efficacy of experimental formulations before conducting ship testing on ocean-going vessels. Therefore, what is needed is to optimize the test procedure or develop an improved rapid test system that can optimally simulate the corrosion process as the ship navigates.

  To date, various test specifications have been implemented.

[Panel test] Static immersion D3623 "Standard test method for adhesion contamination of shallow submerged water panels" issued by the American Society for Testing Materials (ASTM), which standardizes the procedure used for testing marine coatings in aquatic environments It has become. In the system, coated normally flat panels are immersed in a heavily polluted environment as represented by harbor areas, hard deposits (crustaceans, oysters) and soft deposits (seaweed, seaweed, sponges, etc.) In order to determine the resistance exerted by the test coating on the deposits, the sample is left for a long time. The main drawback of this static test is the lack of frictional forces that occur when the ship navigates the sea.

[Test panel evaluation]
ASTM D3623 provides excellent guidelines for evaluating panel conditions after immersion. With the advent of digital photography and the Internet, it has become easier to obtain real-time data on panel status.

  Since the adherent contamination on the panel is related to various environments existing at each site, objective evaluation is a very difficult process. The most reasonable adhesion assessment for which adequate objective data is available is to use a gravimetric method to obtain the number of relative adhesion occurrences. Such data is used by the ASTM method and to complement the subjective assessment obtained from digital photographic records.

[Dynamic test]
ASTM D4938 describes the use of high speed seawater flowing in a pipeline with a coated panel to simulate the corrosion of the coating as a ship navigates the sea.

  Another specification for this test is described in ASTM D4939, commonly known as the “Rotating Drum Test”, which defines a similar simulation method. These test systems function as the industry's core methods and can accurately simulate the stress associated with the coating. This exposure to natural seawater typically consists of alternating static and dynamic cycles of 30 days each over a total period of one year or longer. By collecting the panel after immersion in an elapsed time and adherent contaminated environment, the adhesion resistance performance can be determined. The use of high speed water has disadvantages such as high system manufacturing and operating costs. Rotating drum type test equipment is also expensive, requires the use of curved panels and must have a small number of test panels per drum. The current dynamic test system in use today has the other disadvantage that the corrosion that the device can simulate is only one speed at a time, so testing at different navigation speeds will result in drum speeds during the corrosion test process. Or the water speed needs to be changed.

  In accordance with GB 1457590, the performance of marine paints in relative moving seawater was tested. A disc covered with an anti-adhesion paint was attached to a shaft driven by an electric motor, and then immersed in flowing seawater in a container equipped with an inlet and an overflow valve. The peripheral speed of the disk was 38 knots (43.7 miles / hour). Disadvantages of this test system include, among other things, single speed simulation, lack of biofouling conditions, and lack of high speed vortex generation by containers around the rotating disk.

GB 1457590

  Accordingly, it was an object of the present invention to provide an improved test system for evaluating coatings against biofouling and fluid shear forces.

Provided according to the first aspect of the present invention is a test system for evaluating coatings against biofouling and fluid shear forces in natural seawater (dynamic testing),
-Support structure to hold multiple test panels,
-(A) two or more coaxial circles around the axis and (b) spaced apart from each other in a first row disposed on the support structure in a plane substantially perpendicular to the axis Test panels, which have the same or different coatings on one side, and are arranged so that the first row of test panels on a support structure can rotate about the axis A driving device.

  It should be understood that the axes mentioned here are hypothetical lines and not the three-dimensional material elements of the test system.

  Unlike the provisions of GB 1457590, the test system according to the present invention (i) simulates various speeds, (ii) has the same or at least similar biofouling status as experienced in the actual situation on the hull. Since adjustment and (iii) no container around the system is required, a simulation test substantially free of vortices can be performed even at high speeds.

  Preferably, the support structure of the test system according to the present invention comprises (a) a disc or (b) a concentric support ring for supporting the first row of test panels.

  The first row of test panels is preferably a test of three, four or more coaxial circles so that only one test system according to the present invention can be used to perform three or more speed simulation tests. Consists of panels, each coaxial circle corresponds to an individual test speed at which the test system rotates about its axis.

  In a particularly preferred embodiment of the test system according to the invention, the test system comprises at least a second row of test panels, which are arranged on the support structure axially away from the first row test panel. The support structure comprises (a) a disc or (b) a concentric support ring or (c) other support elements for supporting the second row test panels, and the second row test panels are spaced apart from each other It consists of a single circle of test panels or 2, 3, 4 or more coaxial circles.

  Of course, if two, three or more rows of individual spaced test panels are arranged on the support structure (axially separated from each other), preferably each row (only the first row) But (a) in two or more coaxial circles around the same axis, and (b) in a plane substantially perpendicular to said axis.

  Typically, the first row, second row test panels, and higher row test panels, if present, are supported by the same type of support structure, eg, discs, concentric support rings or other support elements. Is done. In order to support the first row, the second row of test panels, and further rows of test panels, if present, the support structure should preferably be (but not absolutely) the same diameter. If three or more support structures (such as discs) are used (to support three or more test panels), they are preferably arranged equidistant in the axial direction.

  The test system drive according to the present invention preferably comprises a shaft for rotating the first row test panel, the support structure being mounted on the shaft. If there are two or more rows in the test system according to the invention, the shaft is preferably arranged to drive all rows simultaneously. In that case, the (assumed) shaft axis is typically the first row of two or more concentric circle axes about which the first row test panel of the support structure can rotate. (See the description of the preferred embodiment and the drawing below).

  Advantageously, the test panel used in the test system of the present invention is flat on at least one side to which the coating is applied. In general, it is preferable to use a test panel having flat sides.

  The test panels are preferably rectangular or trapezoidal, and the test panels are preferably arranged apart from one another.

Provided from a second aspect of the present invention is a method for evaluating a coating that protects a substrate against underwater biofouling and / or fluid shear forces
-Providing one or more test panels coated with the coating to be evaluated,
Assembling a test system (any of the above embodiments) according to the invention using the provided test panel;
-Immersing the assembled test system in water to bring the test panel into contact with water;
-Rotating the test system at a predetermined rotational speed for a predetermined time; and-evaluating the test panel for the effects of biofouling and / or fluid shear forces during rotation.

  Preferably, the test system is freely immersed in water so that vortex formation is reduced compared to a test setup in which the test system is enclosed in a drum or other container (example based on GB 1457590).

  Of course, the method of the invention can be used when the water is natural seawater or water from a natural river or lake.

  In order to obtain test results at two speeds for one type of coating, at least two test panels, preferably with the same coating, during the assembly of the test system, have two or more in the first row. By assigning test panels to two different circles of the coaxial circle, they are mounted at different positions from the axis.

  In a preferred embodiment of the method according to the invention, at least one concentric test panel of the assembled test system rotates at a peripheral speed in the range of 150-1300 m / min, which corresponds to a typical navigation speed of the ship. To do. Advantageously, the at least two panels of the first row of coaxial circles rotate at a peripheral speed within the said range. More advantageously, all panels of the test system rotate at a peripheral speed within the range.

  A third aspect of the present invention relates to the use of a test system according to the present invention for evaluating marine biofouling prevention coatings against biofouling and fluid shear forces. Preferred embodiments discussed with respect to the first and / or second aspects of the invention are also suitable with respect to this third aspect of the invention.

  The present invention is described in detail below with reference to preferred embodiments and accompanying drawings.

  Preferred embodiments of (a) a test system (hereinafter also referred to as “dynamic test apparatus”) and (b) a method according to the present invention:

  The dynamic test apparatus of the present invention is an important problem associated with dynamic testing, namely increasing the number of panels, the use of flat panels (such as those used in static test methods) and simultaneous ship speeds at various ship speeds. It was devised to deal with the simulation. A schematic diagram of a preferred novel dynamic test apparatus is shown in FIGS. Instead of mounting the curved panel vertically on the outer surface of the “drum”, a rectangular panel is installed horizontally in the support ring structure using bolts to hold the panel to the edge (see FIG. 1). Thereby, it becomes possible to constitute a multiple ring structure that can rotate at a constant speed on the central shaft. As shown in FIG. 2, four ring structures 10, 12, 14 and 16 are driven by the shaft 20 and arranged in the frame structure 30. Each of these four ring structures 10, 12, 14, 16 supports three coaxial rings of a rectangular, spaced apart test panel mounted between coaxial support rings 22, 24, 26, 28. Since the speed experienced by the panel depends on the distance from the center of the support ring structure, panels installed at various locations in the ring structure will experience different speeds and shear stresses. 1a and 1b show the positioning of panels 2 (inner circle), 4 (center circle) and 6 (outer circle) on ring structure 10 (see FIG. 2), and ring structure 10 rotates at a peripheral speed of 37 knots. The equivalent vessel speed for the case (related to the outer coaxial ring of the panel 6 shown) is shown. 1 and 2, the same or similar elements are given the same reference numbers.

  To prevent vortex formation, which reduces the speed of the test panel relative to water, the device should be installed freely, not in drums or other containers. Particularly advantageous is a test in seawater.

  Instead of the ring structure 10, 12, 14, 16, a disk can be used.

  The dynamic test device is advantageously installed on a floating platform and preferably a lifting device is provided to lift the device out of the water for panel mounting, inspection or removal.

  The dynamic test equipment provides an opportunity to investigate shear stress at ship speeds of 18-40 miles / hour or more by simply changing the rotational speed. Flat panels can be used to perform corrosion tests on both sides of the panel. A machine capable of handling 280 standard panels (4 inches x 6 inches) has been designed to these specifications and has been operating in seawater for one year simulating more than 100,000 miles of navigation.

It is a schematic diagram of a preferable new dynamic test apparatus. It is a schematic diagram of a preferable new dynamic test apparatus. It is a schematic diagram of a preferable new dynamic test apparatus.

Claims (12)

In a test system for evaluating coatings against biofouling and fluid shear forces in natural seawater,
-Support structure to hold multiple test panels,
-(A) two or more coaxial circles around the axis and (b) spaced apart from each other in a first row disposed on the support structure in a plane substantially perpendicular to the axis Test panels (2, 4, 6) with the same or different coatings on one side,
A test system comprising a drive arranged such that the first row test panels (2, 4, 6) on a support structure can rotate about the axis;   The test system of claim 1, wherein the support structure comprises (a) a disc (10) or (b) a concentric support ring for supporting a first row of test panels.   The test system according to claim 1 or 2, characterized in that the first row test panels (2, 4, 6) comprise three, four or more coaxial circle test panels.   It consists of at least a second row of test panels, which are arranged on the support structure axially away from the first row test panel (2, 4, 6). Consisting of (a) disc (12) or (b) concentric support ring or (c) other support elements to support the row test panel, and the second row test panel is a single circle of test panels separated from each other Or a test system according to any one of claims 1 to 3, comprising two, three, four or more coaxial circles.   The drive device preferably comprises a shaft (20) for rotating the first row test panel (2, 4, 6), and a support structure is mounted on the shaft (20). Item 5. The test system according to any one of Items 1 to 4.   6. The test system according to claim 1, wherein the test panel is flat on at least one surface to which the coating agent is applied. In a method for evaluating a coating that protects a substrate against underwater biofouling and / or fluid shear forces,
-Providing one or more test panels coated with the coating to be evaluated,
-Assembling the test system of any of the preceding claims using the provided test panel;
-Immersing the assembled test system in water to bring the test panel into contact with water;
An evaluation method comprising the steps of: rotating the test system at a predetermined rotational speed for a predetermined time; and, during rotation, evaluating the test panel for the effects of biofouling and / or fluid shear forces.   8. The method of claim 7, wherein the test system is freely immersed in water such that vortex formation is reduced compared to a test setup in which the test system is enclosed in a drum or other container.   9. The evaluation method according to claim 7, wherein the water is natural seawater or water from a natural river or lake.   10. Evaluation method according to any one of claims 7 to 9, characterized in that at least two test panels with the same coating are mounted at different positions from the shaft during the assembly of the test system.   11. Evaluation method according to any one of claims 7 to 10, characterized in that at least one concentric test panel of the assembled test system rotates at a peripheral speed in the range of 150-1300 m / min. .   Use of a test system according to any one of claims 1 to 6 for evaluating marine biofouling coatings against biofouling and fluid shear forces.

Images